Download G-CO.C.10

Mathematics Curriculum Supplement
Geometry (G-CO.C.10)
Geometry
Mathematics
Highly-Leveraged Standard1
G-CO.C.10 Prove theorems about triangles. Theorems include: measures of interior angles of a triangle sum to 180°;
base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the
third side and half the length; the medians of a triangle meet at a point.
Student Learning Targets:
Students will be able to:
 classify triangles by their sides and angles.
 identify two parallel lines, the midpoint of a segment, the base and base angles of isosceles triangles, and the
midsegments of a triangle.
 prove and apply the triangle sum theorem and the exterior angle theorem.
 prove and apply the idea that the base angles (and two sides) of an isosceles triangle are congruent (and the
converse).
 prove an equilateral triangle is equiangular (and the converse).
 prove and apply the idea that the segment joining midpoints of two sides of a triangle are parallel to the third
side and half the length.
 prove the medians of a triangle meet at the centroid.
 prove the perpendicular bisectors of a triangle meet at the circumcenter.
 prove the altitudes of a triangle meet at the orthocenter.
 prove the angle bisectors of a triangle meet at the incenter.
Performance Level Descriptors
Standard
Minimally Proficient
Partially Proficient
Proficient
Highly Proficient
The Minimally
The Partially Proficient
The Proficient student
The Highly Proficient
Proficient student
student
student
Congruence
G-CO.C
Describes examples of
Determines the validity
Proves theorems about
Applies theorems about
[10]
theorems about
of statements within a
triangles. (Theorems
triangles to a real-life
triangles.
given proof of a theorem include: measures of
context.
about triangles.
interior angles of a
triangle sum to 180°;
base angles of isosceles
triangles are congruent;
the segment joining
midpoints of two sides
of a triangle is parallel to
the third side and half
the length; the medians
of a triangle meet at a
point.)
1
Highly-Leveraged Standards are the most essential for students to learn because they have endurance, leverage and essentiality.
This definition for highly-leveraged standards was adapted from the website of Millis Public Schools, K-12, in Massachusetts, USA.
http://www.millis.k12.ma.us/services/curriculum_assessment/brochures
Specifically for mathematics, the Highly-Leveraged Standards are the Major Content/Clusters as defined by the AZCCRS Grade
Level Focus documents. They should encompass a range of at least 65%-75% for Major Content/Clusters and a range of 25%-35%
for Supporting Cluster Instruction. See the Grade Level Focus documents at:
https://cms.azed.gov/home/GetDocumentFile?id=57069f7baadebe0bccd0a8b5
TUSD Department of Curriculum and Instruction
Curriculum 3.0
Revised 4/30/2017 4:50 PM
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